Confinement Effects on an Electron Transfer Reaction in Nanoporous Carbon Electrodes

Abstract

Nanoconfinement generally leads to drastic effect on the physical and chemical properties of ionic liquids. Here we investigate how the electrochemical reactivity in such media may be impacted inside nanoporous carbon electrodes. To this end, we study a simple electron transfer reaction using molecular dynamics simulations. The electrodes are held at constant electric potential by allowing the atomic charges on the carbon atoms to fluctuate. We show that the $\mathrm{F}{\mathrm{e}}^{3+}/\mathrm{F}{\mathrm{e}}^{2+}$ couple dissolved in an ionic liquid exhibits a deviation with respect to Marcus theory. This behavior is rationalized by the stabilization of a solvation state of the Fe${}^{3+}$ cation in the disordered nanoporous electrode that is not observed in the bulk. The simulation results are fitted with a recently proposed two solvation state model, which allows us to estimate the effect of such a deviation on the kinetics of electron transfer inside nanoporous electrodes.

8 pages, 10 figures

References in corpus (3)

• Biredox ionic liquids with solid-like redox density in the liquid state for high-energy supercapacitors
• Charge Transfer Kinetics at the Solid-Solid Interface in Porous Electrodes
• Capacitance of Nanoporous Carbon-Based Supercapacitors is a Trade-Off Between the Concentration and the Separability of the Ions